[vorbis] developing with libvorbis

[Ed Sweetman]

Sune Foldager wrote:
> On torsdag, mar 27, 2003, at 02:33 Europe/Copenhagen, Ed Sweetman wrote:
> 
>> what about something like this
>>
>> right where it says fwrite in the example decoder
>>
>> if(left > 0){
>>         memcpy(tbuffer+(4096-left),convbuffer,bout*2*vi.channels);
>> left -= bout*2*vi.channels;
>>
>> } else {
>> do my write function with the knowledge that i'm writing 4096 bytes
>> left = 4096;
>> }
> 
> 
> Yes, if you remembered to pass the 'left' variable to the decode 
> function correctly. See below.
> 
>> can i really be sure that it wont try writing 1024 bytes one time and 
>> then 4096 the next?   and other combinations that overrun 4096?
> 
> 
> Well, without having looked at the example in a bit, I am sure there is 
> no problem. The reason being that you specify a maximum size for the 
> decode function. It will NOT decode more than that. It MAY decode less, 
> and it will do so if the frame stops before the buffer is full. So by 
> filling the buffer in a loop like I suggested, __and passing the 'left' 
> parameter to the decode function__ (instead of just 4096), it should 
> work fine.
> 

except i get decodes that can go like this

2304
4096

Now there is no easy way to handle something like that.  Suppose the 
smallest data i can write to the soundcard is 2048bytes. Vorbis is 
giving me stuff that's like 512, 1024  ...and sometimes 2304 and 4096. 
If i dont use all of what it decodes because say it gives me 2304 and 
then 4096, how can i tell it that i didn't read all it's packets and 
that it should start where i left off on it's next cycle of decoding? I 
dont think it's a matter of saying to only seek X amount in the file 
since we're talking about decoded data and there's no easy way to figure 
out where exactly in the file I left off at decoding.  I dont think it's 
possible to leave an offset from a decode.

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